scholarly journals Exploring the Link between Photosystem II Assembly and Translation of the Chloroplast psbA mRNA

Plants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 152 ◽  
Author(s):  
Prakitchai Chotewutmontri ◽  
Rosalind Williams-Carrier ◽  
Alice Barkan
Keyword(s):  
Photosystem Ii ◽  
Water Splitting ◽  
Reaction Center ◽  
Ribosome Profiling ◽  
Oxygenic Photosynthesis ◽  
Dual Roles ◽  
Psii Reaction Center ◽  
Core Proteins ◽  
Prosthetic Groups ◽  
Autoregulatory Mechanism

Photosystem II (PSII) in chloroplasts and cyanobacteria contains approximately fifteen core proteins, which organize numerous pigments and prosthetic groups that mediate the light-driven water-splitting activity that drives oxygenic photosynthesis. The PSII reaction center protein D1 is subject to photodamage, whose repair requires degradation of damaged D1 and its replacement with nascent D1. Mechanisms that couple D1 synthesis with PSII assembly and repair are poorly understood. We address this question by using ribosome profiling to analyze the translation of chloroplast mRNAs in maize and Arabidopsis mutants with defects in PSII assembly. We found that OHP1, OHP2, and HCF244, which comprise a recently elucidated complex involved in PSII assembly and repair, are each required for the recruitment of ribosomes to psbA mRNA, which encodes D1. By contrast, HCF136, which acts upstream of the OHP1/OHP2/HCF244 complex during PSII assembly, does not have this effect. The fact that the OHP1/OHP2/HCF244 complex brings D1 into proximity with three proteins with dual roles in PSII assembly and psbA ribosome recruitment suggests that this complex is the hub of a translational autoregulatory mechanism that coordinates D1 synthesis with need for nascent D1 during PSII biogenesis and repair.

scholarly journals Light-induced psbA translation in plants is triggered by photosystem II damage via an assembly-linked autoregulatory circuit

2020 ◽  
Author(s):  
Prakitchai Chotewutmontri ◽  
Alice Barkan
Keyword(s):  
Photosystem Ii ◽  
Reaction Center ◽  
Action Spectrum ◽  
Photosynthetic Electron Transport ◽  
Oxygenic Photosynthesis ◽  
Translation Elongation ◽  
Reaction Center Protein ◽  
Membrane Complex ◽  
Global Increase ◽  
Autoregulatory Mechanism

AbstractThe D1 reaction center protein of Photosystem II (PSII) is subject to light-induced damage. Degradation of damaged D1 and its replacement by nascent D1 are at the heart of a PSII repair cycle, without which photosynthesis is inhibited. In mature plant chloroplasts, light stimulates the recruitment of ribosomes specifically to psbA mRNA to provide nascent D1 for PSII repair, and also triggers a global increase in translation elongation rate. The light-induced signals that initiate these responses are unclear. We present action spectrum and genetic data indicating that the light-induced recruitment of ribosomes to psbA mRNA is triggered by D1 photodamage, whereas the global stimulation of translation elongation is triggered by photosynthetic electron transport. Furthermore, mutants lacking HCF136, which mediates an early step in D1 assembly, exhibit constitutively high psbA ribosome occupancy in the dark, and differ in this way from mutants lacking PSII for other reasons. These results, together with the recent elucidation of a thylakoid membrane complex that functions in PSII assembly, PSII repair and psbA translation, suggest an autoregulatory mechanism in which the light-induced degradation of D1 relieves repressive interactions between D1 and translational activators in the complex. We suggest that the presence of D1 in this complex coordinates D1 synthesis with the need for nascent D1 during both PSII biogenesis and PSII repair in plant chloroplasts.Significance StatementPhotosystem II (PSII) harbors the water-splitting activity underlying oxygenic photosynthesis. The PSII reaction center protein D1 is subject to photodamage and must be replaced with nascent D1 to maintain photosynthetic activity. How new D1 synthesis is coordinated with D1 damage has been a long-standing question. Our results clarify the nature of the light-induced signal that activates D1 synthesis for PSII repair in plants, and suggest an autoregulatory mechanism in which degradation of damaged D1 relieves a repressive interaction between D1 and translational activators in a complex that functions in PSII assembly and repair. This proposed mechanism comprises a responsive switch that couples D1 synthesis to need for D1 during PSII biogenesis and repair.

scholarly journals Mediator-assisted water oxidation by the ruthenium “blue dimer” cis,cis-[(bpy)2(H2O)RuORu(OH2)(bpy)2]4+

2008 ◽  
Vol 105 (46) ◽  
pp. 17632-17635 ◽  
Author(s):  
Javier J. Concepcion ◽  
Jonah W. Jurss ◽  
Joseph L. Templeton ◽  
Thomas J. Meyer
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Renewable Energy ◽  
Photosystem Ii ◽  
Water Splitting ◽  
Water Oxidation ◽  
Oxygenic Photosynthesis ◽  
Reduced Water ◽  
Insight Into ◽  
Recent Insight

Light-driven water oxidation occurs in oxygenic photosynthesis in photosystem II and provides redox equivalents directed to photosystem I, in which carbon dioxide is reduced. Water oxidation is also essential in artificial photosynthesis and solar fuel-forming reactions, such as water splitting into hydrogen and oxygen (2 H2O + 4 hν → O2 + 2 H2) or water reduction of CO2 to methanol (2 H2O + CO2 + 6 hν → CH3OH + 3/2 O2), or hydrocarbons, which could provide clean, renewable energy. The “blue ruthenium dimer,” cis,cis-[(bpy)2(H2O)RuIIIORuIII(OH2)(bpy)2]4+, was the first well characterized molecule to catalyze water oxidation. On the basis of recent insight into the mechanism, we have devised a strategy for enhancing catalytic rates by using kinetically facile electron-transfer mediators. Rate enhancements by factors of up to ≈30 have been obtained, and preliminary electrochemical experiments have demonstrated that mediator-assisted electrocatalytic water oxidation is also attainable.

scholarly journals Early Archean origin of Photosystem II

2017 ◽  
Author(s):  
Tanai Cardona ◽  
Patricia Sánchez-Baracaldo ◽  
A. William Rutherford ◽  
Anthony W. D. Larkum
Keyword(s):  
Photosystem Ii ◽  
Reaction Center ◽  
Water Oxidation ◽  
Photochemical Reaction ◽  
Early Stage ◽  
Oxygenic Photosynthesis ◽  
Recent Common Ancestor ◽  
Molecular Clocks ◽  
Most Recent Common Ancestor ◽  
History Of

AbstractPhotosystem II is a photochemical reaction center that catalyzes the light-driven oxidation of water to molecular oxygen. Water oxidation is the distinctive photochemical reaction that permitted the evolution of oxygenic photosynthesis and the eventual rise of Eukaryotes. At what point during the history of life an ancestral photosystem evolved the capacity to oxidize water still remains unknown. Here we study the evolution of the core reaction center proteins of Photosystem II using sequence and structural comparisons in combination with Bayesian relaxed molecular clocks. Our results indicate that a homodimeric photosystem with sufficient oxidizing power to split water had already appeared in the early Archean about a billion years before the most recent common ancestor of all described Cyanobacteria capable of oxygenic photosynthesis, and well before the diversification of some of the known groups of anoxygenic photosynthetic bacteria. Based on a structural and functional rationale we hypothesize that this early Archean photosystem was capable of water oxidation and had already evolved some level of protection against the formation of reactive oxygen species, which would place primordial forms of oxygenic photosynthesis at a very early stage in the evolutionary history of life.

Photosystem II: The Reaction Center of Oxygenic Photosynthesis

2013 ◽  
Vol 82 (1) ◽  
pp. 577-606 ◽  
Author(s):  
David J. Vinyard ◽  
Gennady M. Ananyev ◽  
G. Charles Dismukes
Keyword(s):  
Photosystem Ii ◽  
Reaction Center ◽  
Oxygenic Photosynthesis

Effects of water stress and rewatering on turnover and gene expression of photosystem II reaction center polypeptide D1 in Zea mays

1999 ◽  
Vol 26 (4) ◽  
pp. 375 ◽  
Author(s):  
Limin Hao ◽  
Houguo Liang ◽  
Zongling Wang ◽  
Xinmin Liu
Keyword(s):  
Water Stress ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Reaction Center ◽  
Control Level ◽  
State Level ◽  
Transcript Level ◽  
Dot Blot ◽  
Psii Reaction Center ◽  
Severe Water Stress

Photosystem II oxygen evolution capacity, the steady-state level of photosystem II (PSII) reaction center polypeptide D1 and its transcript and template levels inZea mays L. (Xinyu No. 4) under water stress and rewatering were studied. The results indicated that PSII and whole-chain electron transport capacities decreased slightly under moderate water stress and appreciably under severe water stress, and could not recover to control level upon rewatering. The results of western and northern blots showed that the content of PSII reaction center polypeptide D1 changed as a similar pattern to PSII and whole-chain electron transport capacities. Dot blot analysis for DNA showed that there was no obvious response of the template level of D1 to water stress or rewatering. From the results, it was concluded that PSII was the major site affected by water stress, where the functional loss of PSII could be attributed to the reduction of PSII reaction center polypeptide D1, which may be caused by the decrease in its transcript level. Rewatering could only ameliorate slightly under moderate water stress but could not recover to control level under severe water stress.

scholarly journals A Novel Antenna Protein Complex in the Life Cycle of Cyanobacterial Photosystem II

2019 ◽  
Author(s):  
Daniel A. Weisz ◽  
Virginia M. Johnson ◽  
Dariusz M. Niedzwiedzki ◽  
Min Kyung Shinn ◽  
Haijun Liu ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Reaction Center ◽  
Protein Complex ◽  
Analytical Ultracentrifugation ◽  
Current Model ◽  
Cellular Level ◽  
Oxygenic Photosynthesis ◽  
Protective Mechanism ◽  
Chlorophyll Protein ◽  
Pigment Protein Complex

ABSTRACTIn oxygenic photosynthetic organisms, photosystem II (PSII) is a unique membrane protein complex that catalyzes light-driven oxidation of water. PSII undergoes frequent damage due to its demanding photochemistry. However, many facets of its repair and reassembly following photodamage remain unknown. We have discovered a novel PSII subcomplex that lacks five key PSII core reaction center polypeptides: D1, D2, PsbE, PsbF, and PsbI. This pigment-protein complex does contain the PSII core antenna proteins CP47 and CP43, as well as most of their associated low–molecular–mass subunits, and the assembly factor Psb27. Immunoblotting analysis, multiple mass spectrometry techniques, and ultrafast spectroscopic results supported the absence of a functional reaction center in this chlorophyll–protein complex. We therefore refer to it as the ‘no reaction center’ complex (NRC). Additionally, genetic deletion of PsbO on the PSII lumenal side resulted in an increased NRC population, indicative of a faulty PSII repair scheme at the cellular level. Analytical ultracentrifugation studies and clear native acrylamide gel analysis showed that the NRC complex is a stable pigment-protein complex and not a mixture of free CP47 and CP43 proteins. Our finding challenges the current model of the PSII repair cycle and implies an alternative PSII repair strategy. We propose that formation of this pigment-protein complex maximizes PSII repair economy by preserving an intact PSII core antenna shell in a single complex that is available for PSII reassembly, thus minimizing the risk of randomly diluting multiple recycling components in the thylakoid membrane following a photodamage event at the RC.Significance statementPhotosystem II (PSII) converts sunlight into chemical energy, powering nearly all life on Earth. The efficiency of this process is maximized under various environmental conditions by a frequent repair and reassembly cycle that follows inevitable PSII damage even during normal oxygenic photosynthesis. We have isolated a novel pigment protein PSII subcomplex in which, surprisingly, the reaction center (RC) components of PSII are absent. Formation of this stable chlorophyll-protein complex suggests a protective mechanism whereby longer-lived PSII subunits are ‘unplugged’ from the damaged RC to prevent harmful, aberrant photochemistry during RC repair. This finding provides intriguing new insight into how PSII is assembled and rebuilt to optimize its performance to optimally catalyze one of the most challenging reactions in biology.

scholarly journals Photosystem II does not convert nascent oxygen to the poisonous singlet form

2019 ◽  
Author(s):  
Heta Mattila ◽  
Esa Tyystjärvi
Keyword(s):  
Photosystem Ii ◽  
Oxidative Damage ◽  
Triplet State ◽  
Singlet Oxygen ◽  
Water Splitting ◽  
Oxygenic Photosynthesis ◽  
Primary Donor ◽  
Independent Mechanism ◽  
Per Se

AbstractIn the light, the Mn4CaO5 complex of Photosystem II (PSII) splits water producing O2 and the triplet state of the primary donor (3P680) of PSII generates reactive singlet oxygen (1O2). We show that nascent O2 is not converted to 1O2, but originates exclusively from ambient O2, indicating that the sensitivity of PSII to oxidative damage is not a consequence of the water-splitting per se, and showing that the suggested oxygen channels function nearly perfectly, conveying nascent O2 out of the reach of 3P680. This may have been crucial during evolution of oxygenic photosynthesis, as 3P680 cannot be quenched by carotenoids that protect non- oxygenic photosystems. In addition, the data indicate that a 1O2-independent mechanism contributes to the light-induced damage of PSII.

scholarly journals Photosystem II assembly factor HCF136 from A. thaliana at 1.67 Å resolution

2014 ◽  
Vol 70 (a1) ◽  
pp. C1170-C1170
Author(s):  
Roland Bergdahl ◽  
Christin Grundström ◽  
Patrik Storm ◽  
Wolfgang Schröder ◽  
Uwe Sauer
Keyword(s):  
Photosystem Ii ◽  
Water Splitting ◽  
D1 Protein ◽  
Oxygenic Photosynthesis ◽  
Reaction Centre ◽  
Cytochrome B559 ◽  
Irreversible Damage ◽  
Redox Active ◽  
Assembly Factor ◽  
High Level

The High Chlorophyll Fluorescence 136 protein (HCF136) is essential for the assembly and repair of Photosystem II (PSII) and its central reaction centre (RC)[1]. HCF136 is an abundant protein in the thylakoid lumen and has been suggested to directly interact with subunits of the RC. The multi-subunit pigment-protein PSII complex is imbedded in the thylakoid membrane of the oxygenic photosynthetic organisms, and responsible for water splitting during oxygenic photosynthesis. PSII harbours more than 20 different integral and peripheral membrane proteins and its assembly requires a high level of coordination[2]. Two proteins D1 (psbA) and D2 (psbD) form the core of the complex and bind most of the redox-active co-factors. The PSII RC contains, in addition to D1 and D2, the intrinsic PsbI subunit and cytochrome b559. Light is a harmful substrate and subunits are damaged during the water-splitting reaction. The largest irreversible damage is experienced by the central D1 protein that has the highest turnover rate of all thylakoid proteins. Analysis of mutated A. thaliana has identified HCF136 as an essential factor for PSII RC assembly and RC turnover and repair[3]. In order to gain functional and structural insight in the way the HCF136 protein is involved in the PSII repair cycle, we have cloned, expressed, purified and crystallized the HCF136 protein from A. thaliana. Here we present the structure of this doughnut shaped WD40 domain family protein determined at 1.67 Å resolution. Biochemical and biophysical analysis of HCF136 and components of the PSII RC are under way.

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